Use of the Anti-Ice System on A320

[captain87]

When the engine Anti-Ice should be used in flight ?

All type of answers except the following:

"Engine Anti-Ice must be ON prior to and during descent in icing conditions whenever the temperature is below -40°C SAT"

I already know it, but I'd like to be reported practical rules and not phrases from manuals.

Thanks and Kind Regards

[Mäx Reverse]

I'm not sure, whether I get your question right, so I'll just try to explain.

Definition: Icing conditions exist when visible moisture is present and the TAT (inflight) or the OAT (on ground) is below +10°C.

ENG A/I must be ON in all phases of flight when Icing-Conditions exist.

No rule without exemption:

During Climb and Cruise with the SAT below -40°C the ENG A/I may be switched OFF, even when visible moisture is present.

Why? The RAM effect caused by the airframe hitting the air at IAS will heat up by as much as 25K at 350 kts IAS. At SATs below -40°C this resulting TATs are well below freezing point (i.e. remain frozen) and thus by definition icing is not possible.

Prior to and during descent in icing conditions the ENG A/I must be ON even at SATs below -40°C.

That's just a precaution, as Engine Speed is at or near flight idle during descent and the engine ist far more vulnerable to icing (which maybe does not know the definition of icing ;-).

Was that what you wanted to know?

Cheers, MAX

Ah, and by the way: Critical System Operation as ENG A/I ist practically done EXACTLY by phrases of the manual.

[captain87]

Thanks for MaxReverse

Quote: "The RAM effect caused by the airframe hitting the air at IAS will heat up by as much as 25K at 350 kts IAS. At SATs below -40°C this resulting TATs are well below freezing point (i.e. remain frozen) and thus by definition icing is not possible."

Yes you've written exactly what I want to know !

Thank you and Kind Regards !!!

[creamegg]

I went to Lapland with First choice at christmas and was amused to see them de-icing the plane!

I hadn't realised this needed to be done! :O